Re: [PSES] equipment calibration process
In message FCA549BE3ECF9D4CB8CB8576837EA4890A6DCB@ZEUS.cetest.local, ce-test, qualified testing bv - Gert Gremmen g.grem...@cetest.nl writes The principles behind GUM are sound. Agreed. And give workable results without having to invent the wheel yourself. And are accepted by the international metrology worlds (even if EMC cannot be really metrologized). Agreed. It's not the science that bugs me, it's the way language is used to put 'gloss' on what are generally non-rigorous processes, i.e. guesses. Informed guesses, usually, but still guesses. -- This is my travelling signature, adding no superfluous mass. John M Woodgate - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
RE: [PSES] equipment calibration process
My OP said that I did NOT intend to use an 'alternate' calibration method for EMC-related instruments - mostly because of comments during the proceeding years by Mr Woodgate et al on the this listserv. There are some people that *do* read and carefully evaluate advice - scary, huh ?? Brian -Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org]On Behalf Of John M Woodgate Sent: Friday, November 13, 2009 6:02 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] equipment calibration process In message FCA549BE3ECF9D4CB8CB8576837EA4890A6DC8@ZEUS.cetest.local, ce-test, qualified testing bv - Gert Gremmen g.grem...@cetest.nl writes That said; without GUM, no decent traceable internal calibration is possible. So I suggest that you take a look at GUM first: http://en.wikipedia.org/wiki/Measurement_uncertainty I feel very sceptical about this subject. Granted that it is necessary to consider how accurate a result is, but there seems to be a lot of disingenuous language designed to cover up that estimates of accuracy cannot be other than largely arbitrary, because the quantities involved are those which are inherently unknown - if they were known they would not be 'uncertainty'. Consider for example: Type A uncertainties are those that are evaluated by statistical methods, meaning 'guessed using numbers' and Type B uncertainties are evaluated by other means. meaning 'guessed without any numbers being available.' Because of the close association of 'uncertainty' with assessment and certification of laboratories, it is becoming ritualized, with implied presumptions that uncertainty is some sort of 'fall from perfection' or even 'evil'. It isn't; it's an inherent property of this Universe. When threatened with increasing demands for more and more complicated evaluations of uncertainty and/or pressure to reduce it, I suggest to bear in mind that the required accuracy of a result depends entirely on what its to be used for, We don't measure the dimensions of (agricultural) fields to the nearest millimetre, even though with a laser tellurometer, we could measure to even smaller units. I have coined the phrase 'measuring jelly (Jello) with a micrometer' about some EMC tests. This is particularly relevant to EMC, or any other measurements relating to limits. The permissible uncertainty isn't constant: close to the limit it's very small (one hopes), but far from the limit in can indeed be 'agricultural'. If I measure an emission as -20 dB referred to the limit, an uncertainty of +/- 19.5 dB could be tolerated. In practice, +/- 6 dB should be acceptable without question. Another example is sound pressure level. A change of 1 dB is just perceptible under instant comparison. With a 4-hour gap between presentations, some people cannot detect a 3 dB change. But an uncertainty of +/-1 dB is regarded as 'poor' in some circles. End of rant. -- This is my travelling signature, adding no superfluous mass. John M Woodgate - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
RE: [PSES] equipment calibration process
I agree with you John, but some explanation may help. Type A errors are caused by statistical evaluation = example: systematic errors. Systematic errors can -in general- be reduced by a calculable correction plus a new -smaller- uncertainty of type A or B. Type A uncertainty is when you approximate a cable attenuation by 0 dB attenuation with -1 dB uncertainty due to frequency dependency. The specification can be better by creating an attenuation table as function of frequency and linear interpolating in this table plus a type A uncertainty due to linear interpolation plus a type B error due to the instrumentation errors. The interpolation error type A can again be improved by splitting in a correction formula (spline) and a new smaller error. The principles behind GUM are sound. And give workable results without having to invent the wheel yourself. And are accepted by the international metrology worlds (even if EMC cannot be really metrologized). Regards, Ing. Gert Gremmen g.grem...@cetest.nl www.cetest.nl Kiotoweg 363 3047 BG Rotterdam T 31(0)104152426 F 31(0)104154953 Before printing, think about the environment. Van: emc-p...@ieee.org [mailto:emc-p...@ieee.org] Namens John M Woodgate Verzonden: Friday, November 13, 2009 3:02 PM Aan: EMC-PSTC@LISTSERV.IEEE.ORG Onderwerp: Re: [PSES] equipment calibration process In message FCA549BE3ECF9D4CB8CB8576837EA4890A6DC8@ZEUS.cetest.local, ce-test, qualified testing bv - Gert Gremmen g.grem...@cetest.nl writes That said; without GUM, no decent traceable internal calibration is possible. So I suggest that you take a look at GUM first: http://en.wikipedia.org/wiki/Measurement_uncertainty I feel very sceptical about this subject. Granted that it is necessary to consider how accurate a result is, but there seems to be a lot of disingenuous language designed to cover up that estimates of accuracy cannot be other than largely arbitrary, because the quantities involved are those which are inherently unknown - if they were known they would not be 'uncertainty'. Consider for example: Type A uncertainties are those that are evaluated by statistical methods, meaning 'guessed using numbers' and Type B uncertainties are evaluated by other means. meaning 'guessed without any numbers being available.' Because of the close association of 'uncertainty' with assessment and certification of laboratories, it is becoming ritualized, with implied presumptions that uncertainty is some sort of 'fall from perfection' or even 'evil'. It isn't; it's an inherent property of this Universe. When threatened with increasing demands for more and more complicated evaluations of uncertainty and/or pressure to reduce it, I suggest to bear in mind that the required accuracy of a result depends entirely on what its to be used for, We don't measure the dimensions of (agricultural) fields to the nearest millimetre, even though with a laser tellurometer, we could measure to even smaller units. I have coined the phrase 'measuring jelly (Jello) with a micrometer' about some EMC tests. This is particularly relevant to EMC, or any other measurements relating to limits. The permissible uncertainty isn't constant: close to the limit it's very small (one hopes), but far from the limit in can indeed be 'agricultural'. If I measure an emission as -20 dB referred to the limit, an uncertainty of +/- 19.5 dB could be tolerated. In practice, +/- 6 dB should be acceptable without question. Another example is sound pressure level. A change of 1 dB is just perceptible under instant comparison. With a 4-hour gap between presentations, some people cannot detect a 3 dB change. But an uncertainty of +/-1 dB is regarded as 'poor' in some circles. End of rant. -- This is my travelling signature, adding no superfluous mass. John M Woodgate - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org
Re: [PSES] equipment calibration process
In message FCA549BE3ECF9D4CB8CB8576837EA4890A6DC8@ZEUS.cetest.local, ce-test, qualified testing bv - Gert Gremmen g.grem...@cetest.nl writes That said; without GUM, no decent traceable internal calibration is possible. So I suggest that you take a look at GUM first: http://en.wikipedia.org/wiki/Measurement_uncertainty I feel very sceptical about this subject. Granted that it is necessary to consider how accurate a result is, but there seems to be a lot of disingenuous language designed to cover up that estimates of accuracy cannot be other than largely arbitrary, because the quantities involved are those which are inherently unknown - if they were known they would not be 'uncertainty'. Consider for example: Type A uncertainties are those that are evaluated by statistical methods, meaning 'guessed using numbers' and Type B uncertainties are evaluated by other means. meaning 'guessed without any numbers being available.' Because of the close association of 'uncertainty' with assessment and certification of laboratories, it is becoming ritualized, with implied presumptions that uncertainty is some sort of 'fall from perfection' or even 'evil'. It isn't; it's an inherent property of this Universe. When threatened with increasing demands for more and more complicated evaluations of uncertainty and/or pressure to reduce it, I suggest to bear in mind that the required accuracy of a result depends entirely on what its to be used for, We don't measure the dimensions of (agricultural) fields to the nearest millimetre, even though with a laser tellurometer, we could measure to even smaller units. I have coined the phrase 'measuring jelly (Jello) with a micrometer' about some EMC tests. This is particularly relevant to EMC, or any other measurements relating to limits. The permissible uncertainty isn't constant: close to the limit it's very small (one hopes), but far from the limit in can indeed be 'agricultural'. If I measure an emission as -20 dB referred to the limit, an uncertainty of +/- 19.5 dB could be tolerated. In practice, +/- 6 dB should be acceptable without question. Another example is sound pressure level. A change of 1 dB is just perceptible under instant comparison. With a 4-hour gap between presentations, some people cannot detect a 3 dB change. But an uncertainty of +/-1 dB is regarded as 'poor' in some circles. End of rant. -- This is my travelling signature, adding no superfluous mass. John M Woodgate - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
RE: [PSES] equipment calibration process
At first: there is absolutely no reason why internal calibration is not acceptable as long as carried out decently. That said; without GUM, no decent traceable internal calibration is possible. So I suggest that you take a look at GUM first: http://en.wikipedia.org/wiki/Measurement_uncertainty Download tools: http://www.agilent.com/metrology/download.shtml have a larger uncertainty and if this uncertainty is less than is acceptable the bottom line is that YOU decide what is acceptable. A common approach is to calibrate against the manufacturers specs, but if you can live with less accuracy (but traceable = known inaccuracy to int. standards) there is nothing wrong with that. If your measurement receiver is less than 0.5 dB accurate (say 1 dB), you will find out that this has a neglectable impact on the total inaccuracy on the total measurement setup for radiated emissions. Regards, Ing. Gert Gremmen g.grem...@cetest.nl www.cetest.nl Kiotoweg 363 3047 BG Rotterdam T 31(0)104152426 F 31(0)104154953 Before printing, think about the environment. Van: emc-p...@ieee.org [mailto:emc-p...@ieee.org] Namens Andy Clifford Verzonden: Friday, November 13, 2009 10:15 AM Aan: 'Brian O'Connell'; EMC-PSTC@LISTSERV.IEEE.ORG Onderwerp: RE: [PSES] equipment calibration process I don't know what GUM is, but the bottom line is that you should know the uncertainty associated with any test measurements you make, or at least be able to calculate it on demand. If the test equipment used has not be directly calibrated but 'cross calibrated' against a calibrated item it will have a larger uncertainty and if this uncertainty is less than is acceptable the only way around it is to have it directly calibrated. Procedures that address the above should satisfy 17025. Best regards Andy Clifford Conformance Ltd - Product safety, approvals and CE-marking consultants The Old Methodist Chapel, Great Hucklow, Buxton, SK17 8RG England Tel. +44 1298 873800, Fax. +44 1298 873801, www.conformance.co.uk Registered in England, Company No. 3478646 From: Brian O'Connell [mailto:oconne...@tamuracorp.com] Sent: 12 November 2009 18:31 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: [PSES] equipment calibration process Good People, I am attempting to reduce instrument calibration cost/time for non-EMC related equipment. THe proposed process has the calibration contractor perform calibration of a set of 'master instruments' (so are directly traceable to NIST), and other instruments are internally verified using the 'masters'. The proposed process lists a hierarchy of instrument accuracy and precision, and specifies the ranges and scales for each verification of each instrument. Uncertainty is addressed, but GUM is not used. A verification is performed on a subset of the instrument's parameter set. IEC17025 mentions 'vaildated methods' and does not disallow this process; and neither is there anything that specifically recognizes this type of calibration system. My two basic premises are that the measurement uncertainty from a verification is logged at regular intervals, and the process will comply with the requirements list in 5.4.4. I am audited by three agencies and two agree, in principle, with the proposed process. The third does not concur. FWIW, my certificates have a narrow scope - most define of list of Type Tests for several product safety standards. Calibration is distant from my education and experience - so I would appreciate critical thoughts on the use of this as a process internal to a company lab. thanks much, Brian - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald
RE: [PSES] equipment calibration process
I don't know what GUM is, but the bottom line is that you should know the uncertainty associated with any test measurements you make, or at least be able to calculate it on demand. If the test equipment used has not be directly calibrated but 'cross calibrated' against a calibrated item it will have a larger uncertainty and if this uncertainty is less than is acceptable the only way around it is to have it directly calibrated. Procedures that address the above should satisfy 17025. Best regards Andy Clifford Conformance Ltd - Product safety, approvals and CE-marking consultants The Old Methodist Chapel, Great Hucklow, Buxton, SK17 8RG England Tel. +44 1298 873800, Fax. +44 1298 873801, www.conformance.co.uk Registered in England, Company No. 3478646 From: Brian O'Connell [mailto:oconne...@tamuracorp.com] Sent: 12 November 2009 18:31 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: [PSES] equipment calibration process Good People, I am attempting to reduce instrument calibration cost/time for non-EMC related equipment. THe proposed process has the calibration contractor perform calibration of a set of 'master instruments' (so are directly traceable to NIST), and other instruments are internally verified using the 'masters'. The proposed process lists a hierarchy of instrument accuracy and precision, and specifies the ranges and scales for each verification of each instrument. Uncertainty is addressed, but GUM is not used. A verification is performed on a subset of the instrument's parameter set. IEC17025 mentions 'vaildated methods' and does not disallow this process; and neither is there anything that specifically recognizes this type of calibration system. My two basic premises are that the measurement uncertainty from a verification is logged at regular intervals, and the process will comply with the requirements list in 5.4.4. I am audited by three agencies and two agree, in principle, with the proposed process. The third does not concur. FWIW, my certificates have a narrow scope - most define of list of Type Tests for several product safety standards. Calibration is distant from my education and experience - so I would appreciate critical thoughts on the use of this as a process internal to a company lab. thanks much, Brian - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
equipment calibration process
Good People, I am attempting to reduce instrument calibration cost/time for non-EMC related equipment. THe proposed process has the calibration contractor perform calibration of a set of 'master instruments' (so are directly traceable to NIST), and other instruments are internally verified using the 'masters'. The proposed process lists a hierarchy of instrument accuracy and precision, and specifies the ranges and scales for each verification of each instrument. Uncertainty is addressed, but GUM is not used. A verification is performed on a subset of the instrument's parameter set. IEC17025 mentions 'vaildated methods' and does not disallow this process; and neither is there anything that specifically recognizes this type of calibration system. My two basic premises are that the measurement uncertainty from a verification is logged at regular intervals, and the process will comply with the requirements list in 5.4.4. I am audited by three agencies and two agree, in principle, with the proposed process. The third does not concur. FWIW, my certificates have a narrow scope - most define of list of Type Tests for several product safety standards. Calibration is distant from my education and experience - so I would appreciate critical thoughts on the use of this as a process internal to a company lab. thanks much, Brian - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@socal.rr.com Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: More Equipment Calibration
A cost analysis can be used to determine the payback time. I know of no good way to determine the opportunity costs and I have not seen accountants pay much attention to this. Some years ago, at a VERY cheap company, I was able to justify the complete cost of a brand-new spectrum analyzer as less than the expense of calibrating our old 141T and its various plugins (6 month interval) for one year. Cortland This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Equipment Calibration
I read in !emc-pstc that Price, Ed ed.pr...@cubic.com wrote (in b78135310217d511907c0090273f5190d0c...@curly.ds.cubic.com) about 'Equipment Calibration' on Fri, 7 Nov 2003: So I proposed that these items be tagged with some kind of uncalibrated or user verified or no calibration required label. My understanding is that this IS permissible. The gurus of Metrology say this can't be done, our ISO9000 Quality System will not allow this. That may be so, but it doesn't HAVE to prohibit it, AIUI. It DOES have to have a documented procedure for the use of uncalibrated equipment. I can't understand how a customer-oriented quality system can't be crafted to meet the needs of all of the customers of that system. Indeed. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Interested in professional sound reinforcement and distribution? Then go to http://www.isce.org.uk PLEASE do NOT copy news posts to me by E-MAIL! This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Equipment Calibration
Ed, The relevant section of ISO 9001:2000 is clause 7.6 Control of Monitoring and Measuring Devices. If you read this clause (it's only half a page) you will see that calibration of equipment is not an end in itself, but only a means to 'ensure valid results'. If you can do this without the need to calibrate your 'support and stimulus' equipment, then you have no problem with ISO 9001. As you do not use the measurements on the gauges of this equipment for the production of any results, then they cannot have any detrimental effect on 'ensuring valid results'. Most companies prefer to find ways to minimise the number of devices they need to calibrate, in order to keep costs down. (Not that I'm suggesting that your metrology gurus are 'empire-building' ;-). May I suggest that you play the ISO 9001 game by submitting a Corrective Action proposal to amend your current calibration procedures in order to reduce calibration costs, without in any way compromising quality or ISO 9001 compliance. This should bring the problem to the attention of Quality Assurance and bypass the interests of the your Metrology department. Regards, Jon Griver http://www.601help.com The Medical Device Designer's Guide to IEC 60601-1 In some ways, I have the luxury of having a Metrology Department that maintains the periodic calibration on all of my test equipment. OTOH, as a customer of this Metrology Department's product, I would like to have some control over my overhead costs. And my latest bright idea has me getting stomped by the gurus of the status quo. I need to get smarter about how a calibration system works, and how flexible it can be. My lab has about 500 pieces of capital equipment, and the way I see it, all my equipment falls into one of two categories. The first category consists of those instruments which are used to measure the parameters of our company's products, and determine if the performance of those products falls within a range of acceptable tolerance. Data from these measurements is often contractually reported to our customers. Every equipment within this category needs to be maintained on a program of periodic, traceable calibration. But then there's the second category; which consists of support and stimulus equipment. Items here are old analog signal generators, function generators, amplifiers, pulse generators, sweepers and power supplies. To me, none of this equipment needs ANY periodic calibration. I base this on practical usage. Who can accurately read a power supply mechanical 80-amp ammeter that has a 1.5 long scale? Who can set a function generator frequency control that covers 2 decades, logarithmically, in 270 degrees of rotation? If I need to apply a 100 kHz signal in bursts of 2 milliseconds at a 1 Hz rate, I'll use a calibrated, traceable oscilloscope to set the uncalibrated generator to exactly what I need. The same for that power supply; if I need to know the current to 2% or better, I'll use a calibrated resistor and a calibrated DMM. And I couldn't care less about the gain of an RF power amplifier, as long as it pumps out enough power to create the field I need. Now, I'm not trying to justify the use of distorted, unstable or junky equipment. I'm just trying to spend my calibration dollars the most efficient way. And the way I see it, about 1/4 of my equipment fits my definition of not needing periodic calibration because I can monitor the results with calibrated equipment. So I proposed that these items be tagged with some kind of uncalibrated or user verified or no calibration required label. The gurus of Metrology say this can't be done, our ISO9000 Quality System will not allow this. I can't understand how a customer-oriented quality system can't be crafted to meet the needs of all of the customers of that system. And I suppose I'm felling a bit squeezed, what with my customers expecting me to use COTS equipment to function in military environments. I have to get more out of what I have, and the old military concept of everything in sight is on periodic calibration has to yield to current reality. So, am I getting shoveled upon regarding the impossibility of having a category of officially non-calibrated equipment alongside my calibrated equipment? How have you dealt with calibration program costs? Regards, Ed Ed Price ed.pr...@cubic.com WB6WSN NARTE Certified EMC Engineer Technician Electromagnetic Compatibility Lab Cubic Defense Applications San Diego, CA USA 858-505-2780 (Voice) 858-505-1583 (Fax) Military Avionics EMC Is Our Specialty
More Equipment Calibration
Ed, I should add that if the company was starting from scratch, and was just starting the ISO procedure writing, then the no cal way could work smoothly and be the way to go. But if the company already has hundreds of written procedures in place then there could be substantial costs to change things. A cost analysis can be used to determine the payback time. I know of no good way to determine the opportunity costs and I have not seen accountants pay much attention to this. Costs up front: Examining all written procedures Rewritting some procedures Engineering change orders to change procedures Savings that go on forever: Reduced calibration time and a smaller cal department needed Less cal lab equipment to buy, maintain, and cal Less production downtime due to equipment away for calibration Dave Cuthbert Micron Technology -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Price, Ed Sent: Friday, November 07, 2003 2:59 PM To: 'emc-p...@ieee.org' Subject: Equipment Calibration In some ways, I have the luxury of having a Metrology Department that maintains the periodic calibration on all of my test equipment. OTOH, as a customer of this Metrology Department's product, I would like to have some control over my overhead costs. And my latest bright idea has me getting stomped by the gurus of the status quo. I need to get smarter about how a calibration system works, and how flexible it can be. My lab has about 500 pieces of capital equipment, and the way I see it, all my equipment falls into one of two categories. The first category consists of those instruments which are used to measure the parameters of our company's products, and determine if the performance of those products falls within a range of acceptable tolerance. Data from these measurements is often contractually reported to our customers. Every equipment within this category needs to be maintained on a program of periodic, traceable calibration. But then there's the second category; which consists of support and stimulus equipment. Items here are old analog signal generators, function generators, amplifiers, pulse generators, sweepers and power supplies. To me, none of this equipment needs ANY periodic calibration. I base this on practical usage. Who can accurately read a power supply mechanical 80-amp ammeter that has a 1.5 long scale? Who can set a function generator frequency control that covers 2 decades, logarithmically, in 270 degrees of rotation? If I need to apply a 100 kHz signal in bursts of 2 milliseconds at a 1 Hz rate, I'll use a calibrated, traceable oscilloscope to set the uncalibrated generator to exactly what I need. The same for that power supply; if I need to know the current to 2% or better, I'll use a calibrated resistor and a calibrated DMM. And I couldn't care less about the gain of an RF power amplifier, as long as it pumps out enough power to create the field I need. Now, I'm not trying to justify the use of distorted, unstable or junky equipment. I'm just trying to spend my calibration dollars the most efficient way. And the way I see it, about 1/4 of my equipment fits my definition of not needing periodic calibration because I can monitor the results with calibrated equipment. So I proposed that these items be tagged with some kind of uncalibrated or user verified or no calibration required label. The gurus of Metrology say this can't be done, our ISO9000 Quality System will not allow this. I can't understand how a customer-oriented quality system can't be crafted to meet the needs of all of the customers of that system. And I suppose I'm felling a bit squeezed, what with my customers expecting me to use COTS equipment to function in military environments. I have to get more out of what I have, and the old military concept of everything in sight is on periodic calibration has to yield to current reality. So, am I getting shoveled upon regarding the impossibility of having a category of officially non-calibrated equipment alongside my calibrated equipment? How have you dealt with calibration program costs? Regards, Ed Ed Price ed.pr...@cubic.com WB6WSN NARTE Certified EMC Engineer Technician Electromagnetic Compatibility Lab Cubic Defense Applications San Diego, CA USA 858-505-2780 (Voice) 858-505-1583 (Fax) Military Avionics EMC Is Our Specialty
Re: Equipment Calibration
Ed, There is no reason that you cannot do exactly what you propose. The un-calibrated stimulus equipment is irrelevant. As long as you measure and monitor and record with calibrated equipment, it matters not how you obtain the stimulus. In a past life I worked at a ISO 9001 certified manufacturer. All ISO 9001 says is to do what you say and say what you do. So if you have the written procedures in place to describe how you stimulate with NCR equipment, but monitor with currently calibrated equipment, you are doing what your procedures say you are doing and ISO 900x is happy. As for the metrology shop demanding everything be calibrated, ask them to show you specific page, paragraph and rule from what standard this is required. Bet they can't do it. Most likely they will quote some generic paragraph that needs to be translated for them to come up with this requirement. And, most important, you are the customer and end-user. If you do not want your equipment calibrated, that should be your call, not theirs. It should be up to your project reviewer, reporting official, manager, whatever, to decide if you are doing acceptable work with un-calibrated equipment. Maybe you need to raise this up the chain of command. Good luck. Scott Douglas NARTE Certified Product Safety Engineer Email: sdoug...@ptcnh.net Price, Ed wrote: In some ways, I have the luxury of having a Metrology Department that maintains the periodic calibration on all of my test equipment. OTOH, as a customer of this Metrology Department's product, I would like to have some control over my overhead costs. And my latest bright idea has me getting stomped by the gurus of the status quo. I need to get smarter about how a calibration system works, and how flexible it can be. My lab has about 500 pieces of capital equipment, and the way I see it, all my equipment falls into one of two categories. The first category consists of those instruments which are used to measure the parameters of our company's products, and determine if the performance of those products falls within a range of acceptable tolerance. Data from these measurements is often contractually reported to our customers. Every equipment within this category needs to be maintained on a program of periodic, traceable calibration. But then there's the second category; which consists of support and stimulus equipment. Items here are old analog signal generators, function generators, amplifiers, pulse generators, sweepers and power supplies. To me, none of this equipment needs ANY periodic calibration. I base this on practical usage. Who can accurately read a power supply mechanical 80-amp ammeter that has a 1.5 long scale? Who can set a function generator frequency control that covers 2 decades, logarithmically, in 270 degrees of rotation? If I need to apply a 100 kHz signal in bursts of 2 milliseconds at a 1 Hz rate, I'll use a calibrated, traceable oscilloscope to set the uncalibrated generator to exactly what I need. The same for that power supply; if I need to know the current to 2% or better, I'll use a calibrated resistor and a calibrated DMM. And I couldn't care less about the gain of an RF power amplifier, as long as it pumps out enough power to create the field I need. Now, I'm not trying to justify the use of distorted, unstable or junky equipment. I'm just trying to spend my calibration dollars the most efficient way. And the way I see it, about 1/4 of my equipment fits my definition of not needing periodic calibration because I can monitor the results with calibrated equipment. So I proposed that these items be tagged with some kind of uncalibrated or user verified or no calibration required label. The gurus of Metrology say this can't be done, our ISO9000 Quality System will not allow this. I can't understand how a customer-oriented quality system can't be crafted to meet the needs of all of the customers of that system. And I suppose I'm felling a bit squeezed, what with my customers expecting me to use COTS equipment to function in military environments. I have to get more out of what I have, and the old military concept of everything in sight is on periodic calibration has to yield to current reality. So, am I getting shoveled upon regarding the impossibility of having a category of officially non-calibrated equipment alongside my calibrated equipment? How have you dealt with calibration program costs? Regards, Ed Ed Price ed.pr...@cubic.com WB6WSN NARTE Certified EMC Engineer Technician Electromagnetic Compatibility Lab Cubic Defense Applications San Diego, CA USA 858-505-2780 (Voice) 858-505-1583 (Fax) Military Avionics EMC Is Our Specialty
RE: Equipment Calibration
Ed, I have dealt with this before. I will make the case first for not going to no calibration required. Being ISO certified your company no doubt has written procedures for all production work. Any procedures that reference equipment that would go to a no cal status will have to be examined and possibly modified. No production measurement can be done with the no cal equipment, even if the accuracy needed is only 50%. With no cal, it is not traceable to NIST at any accuracy. If the procedures already use other equipment to confirm the settings of the no cal equipment then you are OK. Otherwise, procedures must be rewritten. You will have to compare the cost of modifying the procedures- the time for the sustaining engineers to look over all of them, change some of them, run the changes through the ECO system, and the opportunity-cost of all of these people being taken away from their normal work flow. So, perhaps the no cal approach is too costly. But, there might be another way. Based on the records of the calibration department the calibration cycles could be extended on some equipment. If the past history (they do keep the data from all calibrations, I assume) shows that the equipment is likely to remain in cal for a longer period of time then this can work. A good cal lab will measure a piece of equipment before making any adjustments. This data is used to see if the equipment is falling out of cal during the cal interval or is broken. There is a difference between calibration and a calibration adjustment. Some standards never receive an adjustment (such as a Thomas 1 ohm standard). The calibration is plotted over time. The cost here is the time taken by the calibration department to check the cal records of the 125 pieces of gear. I use this method for things like pulse generators and pattern generators. The main reason being to not incur the downtime of having the gear sent to be calibrated. Another technique to lower costs is to perform a limited calibration. Only those parameters that matter to you are checked. For example, if you never use any handheld digital meters for AC current measurement this can be skipped. A limited calibration sticker should be affixed and records kept in the cal department. The cost here is that procedures and record keeping in the cal department need modification and all production procedures need reviewing to ensure that no written procedure is compromised. So, in my opinion, the cleanest path is to leave things as they are. No extra work involved, the cal lab is happy, and having everything calibrated makes things simpler for future production and procedure development. Dave Cuthbert Micron Technology From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Price, Ed Sent: Friday, November 07, 2003 2:59 PM To: 'emc-p...@ieee.org' Subject: Equipment Calibration In some ways, I have the luxury of having a Metrology Department that maintains the periodic calibration on all of my test equipment. OTOH, as a customer of this Metrology Department's product, I would like to have some control over my overhead costs. And my latest bright idea has me getting stomped by the gurus of the status quo. I need to get smarter about how a calibration system works, and how flexible it can be. My lab has about 500 pieces of capital equipment, and the way I see it, all my equipment falls into one of two categories. The first category consists of those instruments which are used to measure the parameters of our company's products, and determine if the performance of those products falls within a range of acceptable tolerance. Data from these measurements is often contractually reported to our customers. Every equipment within this category needs to be maintained on a program of periodic, traceable calibration. But then there's the second category; which consists of support and stimulus equipment. Items here are old analog signal generators, function generators, amplifiers, pulse generators, sweepers and power supplies. To me, none of this equipment needs ANY periodic calibration. I base this on practical usage. Who can accurately read a power supply mechanical 80-amp ammeter that has a 1.5 long scale? Who can set a function generator frequency control that covers 2 decades, logarithmically, in 270 degrees of rotation? If I need to apply a 100 kHz signal in bursts of 2 milliseconds at a 1 Hz rate, I'll use a calibrated, traceable oscilloscope to set the uncalibrated generator to exactly what I need. The same for that power supply; if I need to know the current to 2% or better, I'll use a calibrated resistor and a calibrated DMM. And I couldn't care less about the gain of an RF power amplifier, as long as it pumps out enough power to create the field I need. Now, I'm not trying to justify the use of distorted, unstable or junky equipment. I'm just trying to spend my calibration dollars the most efficient way
Re: Equipment Calibration
Ed, I would agree with you and with the other people who have responded to your letter - I don't see any issues with not calibrating supplies and generators as long as you are using a calibrated meter/scope/measuring device/whatever to monitor the uncalibrated instrument. I currently work for a small design and manufacturing company in Portland, Oregon and prior to that I worked for a third-party regulatory agency, and in both cases it was considered acceptable to use uncalibrated sources as long as they were monitored in testing by a calibrated meter of some type and the meters used were recorded in the datasheet package along with calibration dates, etc. At the regulatory agency there were sometimes calibrations of things that didn't really seem to need calibration, like yearly calibrations of 20-lb weights for pull tests, but I was told by one of the lab staff that once they got a scale and had that calibrated yearly, they weren't required to submit the weights themselves for calibration. This is almost exactly the scenario you are describing . . . . use a calibrated measuring device during a particular test to measure a stimulus and the stimulus itself shouldn't have to be separately calibrated. I don't have any experience with ISO 9000 procedures, so I guess it might be possible that a particular company's procedure insists on the calibration of every piece of equipment (though it seems pretty unlikely). I know I've never heard of that being a general ISO requirement that everyone has to follow. Has the Metrology Department declared this requirement off the cuff, or have they been able to point to a specific clause or clauses in the company policy manual or ISO 9000 handbook or standard procedures that says you MUST calibrate all sources? -Camille Portland, Oregon Price, Ed ed.pr...@cubic.com wrote: In some ways, I have the luxury of having a Metrology Department that maintains the periodic calibration on all of my test equipment. OTOH, as a customer of this Metrology Department's product, I would like to have some control over my overhead costs. And my latest bright idea has me getting stomped by the gurus of the status quo. I need to get smarter about how a calibration system works, and how flexible it can be. My lab has about 500 pieces of capital equipment, and the way I see it, all my equipment falls into one of two categories. The first category consists of those instruments which are used to measure the parameters of our company's products, and determine if the performance of those products falls within a range of acceptable tolerance. Data from these measurements is often contractually reported to our customers. Every equipment within this category needs to be maintained on a program of periodic, traceable calibration. But then there's the second category; which consists of support and stimulus equipment. Items here are old analog signal generators, function generators, amplifiers, pulse generators, sweepers and power supplies. To me, none of this equipment needs ANY periodic calibration. I base this on practical usage. Who can accurately read a power supply mechanical 80-amp ammeter that has a 1.5 long scale? Who can set a function generator frequency control that covers 2 decades, logarithmically, in 270 degrees of rotation? If I need to apply a 100 kHz signal in bursts of 2 milliseconds at a 1 Hz rate, I'll use a calibrated, traceable oscilloscope to set the uncalibrated generator to exactly what I need. The same for that power supply; if I need to know the current to 2% or better, I'll use a calibrated resistor and a calibrated DMM. And I couldn't care less about the gain of an RF power amplifier, as long as it pumps out enough power to! create the field I need. Now, I'm not trying to justify the use of distorted, unstable or junky equipment. I'm just trying to spend my calibration dollars the most efficient way. And the way I see it, about 1/4 of my equipment fits my definition of not needing periodic calibration because I can monitor the results with calibrated equipment. So I proposed that these items be tagged with some kind of uncalibrated or user verified or no calibration required label. The gurus of Metrology say this can't be done, our ISO9000 Quality System will not allow this. I can't understand how a customer-oriented quality system can't be crafted to meet the needs of all of the customers of that system. And I suppose I'm felling a bit squeezed, what with my customers expecting me to use COTS equipment to function in military environments. I have to get more out of what I have, and the old military concept of everything in sight is on periodic calibration has to yield to current reality. So, am I getting shoveled upon regarding the impossibility of having a category of officially non-calibrated equipment alongside my calibrated equipment? How have you dealt with calibration program costs? Regards, Ed Ed Price ed.pr...@cubic.com
Re: Equipment Calibration
Intereseting, I think the ISO and in particular the lab guides indicate simply that if equipment doesn't need calibration it is marked as such. The other stuff obviously must have a cal sticker on it. There are all kinds of lab supplies lying around just to power products during test etc that don't require a calibrations so it seems unlikely that it would be prohibited. Just changed companies so I don't have access to my old documents just yet - so shooting from memory so double check. Gary From: Price, Ed ed.pr...@cubic.com Reply-To: Price, Ed ed.pr...@cubic.com To: 'emc-p...@ieee.org' emc-p...@ieee.org Subject: Equipment Calibration Date: Fri, 7 Nov 2003 13:58:35 -0800 In some ways, I have the luxury of having a Metrology Department that maintains the periodic calibration on all of my test equipment. OTOH, as a customer of this Metrology Department's product, I would like to have some control over my overhead costs. And my latest bright idea has me getting stomped by the gurus of the status quo. I need to get smarter about how a calibration system works, and how flexible it can be. My lab has about 500 pieces of capital equipment, and the way I see it, all my equipment falls into one of two categories. The first category consists of those instruments which are used to measure the parameters of our company's products, and determine if the performance of those products falls within a range of acceptable tolerance. Data from these measurements is often contractually reported to our customers. Every equipment within this category needs to be maintained on a program of periodic, traceable calibration. But then there's the second category; which consists of support and stimulus equipment. Items here are old analog signal generators, function generators, amplifiers, pulse generators, sweepers and power supplies. To me, none of this equipment needs ANY periodic calibration. I base this on practical usage. Who can accurately read a power supply mechanical 80-amp ammeter that has a 1.5 long scale? Who can set a function generator frequency control that covers 2 decades, logarithmically, in 270 degrees of rotation? If I need to apply a 100 kHz signal in bursts of 2 milliseconds at a 1 Hz rate, I'll use a calibrated, traceable oscilloscope to set the uncalibrated generator to exactly what I need. The same for that power supply; if I need to know the current to 2% or better, I'll use a calibrated resistor and a calibrated DMM. And I couldn't care less about the gain of an RF power amplifier, as long as it pumps out enough power to create the field I need. Now, I'm not trying to justify the use of distorted, unstable or junky equipment. I'm just trying to spend my calibration dollars the most efficient way. And the way I see it, about 1/4 of my equipment fits my definition of not needing periodic calibration because I can monitor the results with calibrated equipment. So I proposed that these items be tagged with some kind of uncalibrated or user verified or no calibration required label. The gurus of Metrology say this can't be done, our ISO9000 Quality System will not allow this. I can't understand how a customer-oriented quality system can't be crafted to meet the needs of all of the customers of that system. And I suppose I'm felling a bit squeezed, what with my customers expecting me to use COTS equipment to function in military environments. I have to get more out of what I have, and the old military concept of everything in sight is on periodic calibration has to yield to current reality. So, am I getting shoveled upon regarding the impossibility of having a category of officially non-calibrated equipment alongside my calibrated equipment? How have you dealt with calibration program costs? Regards, Ed Ed Price ed.pr...@cubic.com WB6WSN NARTE Certified EMC Engineer Technician Electromagnetic Compatibility Lab Cubic Defense Applications San Diego, CA USA 858-505-2780 (Voice) 858-505-1583 (Fax) Military Avionics EMC Is Our Specialty _ Concerned that messages may bounce because your Hotmail account is over limit? Get Hotmail Extra Storage! http://join.msn.com/?PAGE=features/es This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Equipment Calibration
In some ways, I have the luxury of having a Metrology Department that maintains the periodic calibration on all of my test equipment. OTOH, as a customer of this Metrology Department's product, I would like to have some control over my overhead costs. And my latest bright idea has me getting stomped by the gurus of the status quo. I need to get smarter about how a calibration system works, and how flexible it can be. My lab has about 500 pieces of capital equipment, and the way I see it, all my equipment falls into one of two categories. The first category consists of those instruments which are used to measure the parameters of our company's products, and determine if the performance of those products falls within a range of acceptable tolerance. Data from these measurements is often contractually reported to our customers. Every equipment within this category needs to be maintained on a program of periodic, traceable calibration. But then there's the second category; which consists of support and stimulus equipment. Items here are old analog signal generators, function generators, amplifiers, pulse generators, sweepers and power supplies. To me, none of this equipment needs ANY periodic calibration. I base this on practical usage. Who can accurately read a power supply mechanical 80-amp ammeter that has a 1.5 long scale? Who can set a function generator frequency control that covers 2 decades, logarithmically, in 270 degrees of rotation? If I need to apply a 100 kHz signal in bursts of 2 milliseconds at a 1 Hz rate, I'll use a calibrated, traceable oscilloscope to set the uncalibrated generator to exactly what I need. The same for that power supply; if I need to know the current to 2% or better, I'll use a calibrated resistor and a calibrated DMM. And I couldn't care less about the gain of an RF power amplifier, as long as it pumps out enough power to create the field I need. Now, I'm not trying to justify the use of distorted, unstable or junky equipment. I'm just trying to spend my calibration dollars the most efficient way. And the way I see it, about 1/4 of my equipment fits my definition of not needing periodic calibration because I can monitor the results with calibrated equipment. So I proposed that these items be tagged with some kind of uncalibrated or user verified or no calibration required label. The gurus of Metrology say this can't be done, our ISO9000 Quality System will not allow this. I can't understand how a customer-oriented quality system can't be crafted to meet the needs of all of the customers of that system. And I suppose I'm felling a bit squeezed, what with my customers expecting me to use COTS equipment to function in military environments. I have to get more out of what I have, and the old military concept of everything in sight is on periodic calibration has to yield to current reality. So, am I getting shoveled upon regarding the impossibility of having a category of officially non-calibrated equipment alongside my calibrated equipment? How have you dealt with calibration program costs? Regards, Ed Ed Price ed.pr...@cubic.com WB6WSN NARTE Certified EMC Engineer Technician Electromagnetic Compatibility Lab Cubic Defense Applications San Diego, CA USA 858-505-2780 (Voice) 858-505-1583 (Fax) Military Avionics EMC Is Our Specialty
